Basic algorithm to count cards in Blackjack.

cardCounting.js

var count = 0;

function cc(card) {
  switch (card) {
    case 2:
    case 3:
    case 4:
    case 5:
    case 6:
      count++;
      break;
    case 10:
    case 'J':
    case 'Q':
    case 'K':
    case 'A':
      count--;
      break;
  }
  
  if (count <= 0) {
    return "Hold";
  }
  
  return "Change Me";
}

// Add/remove calls to test your function.
// Note: Only the last will display
cc(2); cc(3); cc(7); cc('K'); cc('A');